Controlling low-temperature tunneling dynamics with external fields

被引:33
作者
Morillo, M [1 ]
Cukier, RI [1 ]
机构
[1] MICHIGAN STATE UNIV,CTR FUNDAMENTAL MAT RES,E LANSING,MI 48824
来源
PHYSICAL REVIEW B | 1996年 / 54卷 / 19期
关键词
D O I
10.1103/PhysRevB.54.13962
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
The tunneling of a particle between two states, as influenced by coupling the particle to an external field, is investigated. A spin-boson Hamiltonian is used to describe the tunnel system and its interaction with a medium and is augmented by a term coupling the dipole moment of the particle to the external held. A projection operator method is introduced that provides equations of motion for the particle's density matrix and permits discussion of external held effects on tunneling even at very low temperatures. These equations of motion can exhibit solutions characterized by population relaxation with a rate constant that is an average over the period of the external held. As an application of this theory, the modification by an external field of the tunneling rate of a defect in a metal, where the system-medium interaction is characterized by an Ohmic spectrum, is evaluated. At sufficiently low temperatures, for experimentally relevant parameter values, suitably chosen (constant and/or sinusoidal), external fields can greatly suppress or enhance the tunneling rate relative to the field-independent value.
引用
收藏
页码:13962 / 13973
页数:12
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